The present invention relates to a device for transferring objects in gaseous atmospheres with a controlled content of impurities, particularly plastic bottles intended for the pharmaceutical industry.
As a matter of fact, for packaging medicines and other pharmaceutical products, bottles are used which contain air with a very low percentage of impurities. In other words, the air contained in bottles designed for the pharmaceutical industry should have a specific level of particulate purity.
The same thing applies to the production and packaging of surgical materials, or components designed for the electronics industry, for example.
The particulate purity of the air or of a gas is defined and classified by the French standard NF-X 44-101.
Under such standard, the dust content of a gas is defined by the numerical concentration of floating particles, the sizes of which exceed specified granulometric levels (generally speaking 5 microns and 0.5 microns). The limit for each class of dust content is established by specifying a maximum numerical concentration for each of the particle size classes.
The NF-X 44-101 standard provides a simplified procedure, defining three classes in accordance with the table below:
______________________________________ Maximum concentration in number of Class of particles per cubic meter for each level dust content 0.5.mu. 5.mu. ______________________________________ 4,000,000 4,000,000 25,000 400,000 400,000 2,500 4,000 4,000 25 ______________________________________
In the following text, classes defined by means of this simplified procedure are used to categorize the particulate purity of the air in various parts of the invention to explain a preferred way in which to implement the invention.
The pharmaceutical industry stipulates that manufacturers must supply bottles containing air which is as pure as possible, corresponding at most to class 400,000.
With this in mind, manufacturers install their production machinery in a sealed enclosure which is continuously swept out by a laminar stream of class 400,000 air.
The manufactured bottles are manually placed in a plastic bag by a technician who enters the enclosure through an airlock, closes the bag and carries the bags out of the sealed enclosure through the airlock. The technician must take great care regarding his personal hygiene and clothing: gloves, white smock or one-piece garment with all particles removed, i.e. free of any particles which could adhere to them; overshoes, headgear, mask etc.
Despite all these precautions, which represent a considerable investment in themselves, such a procedure represents a not inconsiderable risk of accidental pollution of the bottles. Manufacturers can guarantee that their bottles have been produced in conditions which meet the specified standards of purity, but cannot guarantee the result.